I like the look of this board, template, fuller volume, rounded pin. Flatter rocker... single to double concave....
Yes, this is a "short board" "fun board". But blow this up to about 9'6 x 29"
Or start off with a 6'6 x 20"1/2 x 2"7/8 blown up by a factor of about 1.45 to 1.50, becomes,
9'6 x 29"1/2 x 4", but go thicker, towards 4"3/8.
You'll have a board that handles well in larger surf. Suggested construction, EPS Core & Epoxy Resin, with a 3/8 inch stringer, or 10mm stringer. Or perhaps 3 x 1/4 inch stringers.
------
Edit: Ah Ha !! You said, heavier surfer, not heavier surf !! My reply was orientated to "heavier surf" !
Yes, Mana would be good for heavier surfer... !